I have a 1983 Manufacture GE Weathertron Elite...outdoor heat pump, crawlspace coils, etc. It started acting up the other day. Having been away a day, I don't know if there was a storm involved, or it's just the annual glitch.

During cooling cycle, initially it is fine. But after a while, the solenoid begins clicking on and off, causing the reversing valve to kick in repeatedly. If turned off, and allowed to sit, and then restarted, will cool normally, and quietly for the first 5-10 minutes (pipe going into house is very cold), then eventually the solenoid will click a tiny bit, slightly, just a blip, then get worse over the next few minutes. I put a voltmeter to the power leads to the solenoid and things are steady at 26.1v...until there's a click, then it's a dip to 24, or 19, or 9 for the loud ones where it almost completely reverses, then when fully reverses, it's zero. But power returns shortly after sometimes...sometimes not. The 240v defrost timer is rotating, and other than minor pitting on the contact pair I could see (one set was closed the other open), did not seem to look bad.

What would cause this kind of behavior? If it is the solenoid coil, how to do I get the solenoid off the pin there? (open frame coil, Alco AMF-24v 12W) The only thing I see is what looks like a silver cap on the end preventing it from coming off to the rear of the valve, but sure doesn't seen to screw on or off?

Could the interior thermostat, or one of the 2 thermostats there inside the heat pump cause this intermittent powering of the solenoid?

A) one on thin pipe riser to outside coilsB) one on thick pipe near expansion area (?) compressor

Something else? This is attached to a load controller. They don't go bad do they? Wouldn't cause this behavior I wouldn't think. Low refrigerant would not do this would it? I know this is a lot to throw out in a single post, but I'm just trying to work it out. Thanks for any suggestions. I'm kind of in a bind right now, money wise. A defrost control is pricey even at DIY price, about $180 for the Trane CNT-2236 which replaces this older 240 v clock type. I can see it spinning though...

I would think solenoid is faulty given the behavior, except even if it was going open, the voltage should still be 26v at the supply side where I am measuring it?

theduke03 -> You need to determine where the voltage is dropping. It sounds like it> could be the defrost control or the thermostat but could be a loose wire> connection somewhere too. Good luck!

Well, cross your fingers, I think it's working again. No clicks or weirdness in over 30 minutes now. And your latter is probably the cause...loose or corroded wiring. I wonder why it works initially though?

I called a friend who has a brother who works HVAC...he said likely either the 24v secondary is dropping out , or defrost control...so I went to Radio Shack, got some 28v lamps...solenoid was losing power. Defrost control never clicked the relay ever during the outs...so...

Went under the house, pulled it all apart there, wiggled some wires, tightened some wire caps, hooked up the 28v bulb, and ran it all again, but because the cover was off, it was intaking cooler crawlspace air...it only clicked once, but started freezing up big time on the hot/cold pipe. So, went back under house, undid all that, loosened and retightened the HVAC transformer to fine wire (24v wires) junction (bad corroded)...and bolted it all back together.

Tightened nuts on heat pump wires outside (24v). Works. Now if I put the heat pump casing back together and it stops working, I'll be bummed, but know it's local to the 24v interface and the wiring there in that grouping I guess. It's a bird's nest.

Solenoid is running kind of hot I guess, never felt it before in all these years, but I don't know how hot a continual service coil should get. I still don't know how to remove it in case I ever need to replace. How does one remove such type of solenoid coil? (Open frame type)...does that silver cap on the end unscrew, or pop off allowing it to slide off? Kind of wonder, since one would think it would have a nut-type appearance if unscrewed...Surely it was made to be removable. (Alco AMF 24v 12W)

Ok, something's wrong somewhere. I am not sure the A/C guy who rewired the contactor last year did it right...when the outside unit is powered off by the indoor thermostat, the solenoid is still engaged outside...and hot... now clicking again.

Is the solenoid on the Reversing valve supposed to remain energized even when the unit is not currently cycling?

With lights wired to O and B, and to solenoid terminal....turned on main again (24v power)... just let it sit, without starting the unit...both lights began flickering, solenoid a clicking. So will again check underneath house again...must be between the terminal where it all connects up to underhouse unit, unless it's something in the thermostat 7 conductor wiring in the wall (%# mouse chewed? )...going to thermostat.

GE Weathertron - must be between the terminal where it all connects> up to underhouse unit, unless it's something in the thermostat 7 conductor> wiring in the wall (%# mouse chewed? )...going to thermostat.

There's a 24v P & B KU-2016 5A relay inside the fan unit under the house...which clicks at the same time that power to the orange is lost...I think. When I was disconnecting the orange, and closing them back, I think it clicked.

Remains un-activated when the loss of orange power and clicking is going on though.

I don't know where this loose orange wire might be, unless it's chewed or broken in the wall or something?

Stumped now. No loose connection found yet.

Secondary to 24v transformer if going out, would not result in a constant light/voltage for red and blue (C) but failure for Orange and blue (C)?

Found the problem area finally, I believe, was one or two trouble points in a very old 7 way splice to outside unit outside the house in a tape sarcophagus..18/7 conductor, butt-joint crimp tubes. I cut all that out, stripped, soldered and covered using heat shrink tubing and tape. Unit is running now, seems to work correctly again.